local ffi = require 'cffi'

local libzmq = ffi.load("libzmq.so")
ffi.cdef [[

void *zmq_ctx_new (void);
int zmq_ctx_term (void *context_);
int zmq_ctx_shutdown (void *context_);
int zmq_ctx_set (void *context_, int option_, int optval_);
int zmq_ctx_get (void *context_, int option_);

struct zmq_msg_t
{
unsigned char _[64];
};

struct zmq_pollitem
{
    void* socket;
    int fd;
    short events;
    short revents;
};

int zmq_msg_init (struct zmq_msg_t *msg_);
int zmq_msg_init_size (struct zmq_msg_t *msg_, size_t size_);

int zmq_msg_send (struct zmq_msg_t *msg_, void *s_, int flags_);
int zmq_msg_recv (struct zmq_msg_t *msg_, void *s_, int flags_);
int zmq_msg_close (struct zmq_msg_t *msg_);
int zmq_msg_move (struct zmq_msg_t *dest_, struct zmq_msg_t *src_);
int zmq_msg_copy (struct zmq_msg_t *dest_, struct zmq_msg_t *src_);
void *zmq_msg_data (struct zmq_msg_t *msg_);
size_t zmq_msg_size (const struct zmq_msg_t *msg_);
int zmq_msg_more (const struct zmq_msg_t *msg_);
int zmq_msg_get (const struct zmq_msg_t *msg_, int property_);
int zmq_msg_set (struct zmq_msg_t *msg_, int property_, int optval_);
const char *zmq_msg_gets (const struct zmq_msg_t *msg_,
                                    const char *property_);
void *zmq_socket (void *, int type_);
int zmq_close (void *s_);
int zmq_setsockopt (void *s_, int option_, const void *optval_, size_t optvallen_);
int zmq_bind (void *s_, const char *addr_);
int zmq_connect (void *s_, const char *addr_);
int zmq_unbind (void *s_, const char *addr_);
int zmq_disconnect (void *s_, const char *addr_);
int zmq_send (void *s_, const void *buf_, size_t len_, int flags_);
int zmq_send_const (void *s_, const void *buf_, size_t len_, int flags_);
int zmq_recv (void *s_, void *buf_, size_t len_, int flags_);
int zmq_poll (struct zmq_pollitem *items_, int n_, long timeout_);
int zmq_errno();

]]

local ZMQ_PAIR = 0
local ZMQ_PUB = 1
local ZMQ_SUB = 2
local ZMQ_REQ = 3
local ZMQ_REP = 4
local ZMQ_DEALER = 5
local ZMQ_ROUTER = 6
local ZMQ_PULL = 7
local ZMQ_PUSH = 8
local ZMQ_XPUB = 9
local ZMQ_XSUB = 10
local ZMQ_STREAM = 11

local ZMQ_POLLIN = 1
local ZMQ_POLLOUT = 2
local ZMQ_POLLERR = 4

local ZMQ_SNDMORE = 2

local ZMQ_ROUTING_ID = 5
local ZMQ_LINGER = 17
local ZMQ_RCVTIMEO = 27
local ZMQ_SNDTIMEO = 28
local ZMQ_ROUTER_MANDATORY = 33

local function check_if_error(value, success_value, err_value)
    if value == err_value then
        return nil, libzmq.zmq_errno()
    else
        return success_value, nil
    end
end

local function ctx_term(ctx)
    libzmq.zmq_ctx_term(ctx.ctx)
end

local function socket_bind(socket, endpoint)
    return check_if_error(
        libzmq.zmq_bind(socket.socket, endpoint), nil, -1)
end

local function socket_connect(socket, endpoint)
    return check_if_error(
        libzmq.zmq_connect(socket.socket, endpoint), nil, -1)
end

local function socket_setsockopt_int(socket, option_name, value)
    local arr = ffi.new("int[1]", value);
    if not option_name then
        return nil, -1
    end
    return check_if_error(
        libzmq.zmq_setsockopt(socket.socket, option_name, arr, 4),
        nil, -1)
end

local function socket_setsockopt_str(socket, option_name, value)
    local arr = ffi.new("uint8_t[?]", #value)
    ffi.copy(arr, value, #value)
    return check_if_error(
        libzmq.zmq_setsockopt(socket.socket, option_name, arr, #value),
        nil, -1)
end

local function socket_close(socket)
    return check_if_error(
        libzmq.zmq_close(socket.socket), nil, -1)
end

local function socket_disconnect(socket)
    return check_if_error(
        libzmq.zmq_disconnect(socket.socket), nil, -1)
end

local function socket_send(socket, message)
    local rc = 0
    if #message > 1 then
        for i = 1, #message - 1 do
            rc = libzmq.zmq_send(socket.socket, message[i], string.len(message[i]),
                          ZMQ_SNDMORE)
            if rc < 0 then
                print(rc)
                return nil, libzmq.zmq_errno()
            end
        end
    end
    rc = libzmq.zmq_send(socket.socket, message[#message], string.len(message[#message]), 0)
    if rc < 0 then
        return nil, libzmq.zmq_errno()
    end
    return nil, nil
end

local function socket_recv(socket)

    local msg = {}
    local more = false
    repeat
        local part = ffi.new("struct zmq_msg_t[1]")
        if not part then
            return nil, -1
        end
        if not libzmq.zmq_msg_init(part) then
            return nil, libzmq.zmq_errno()
        end
        local rc = libzmq.zmq_msg_recv(part, socket.socket, 0)
        if rc < 0 then
            return nil, libzmq.zmq_errno()
        else
            local len = libzmq.zmq_msg_size(part)
            msg[#msg + 1] = ffi.string(libzmq.zmq_msg_data(part), len)
            more = (libzmq.zmq_msg_more(part) == 0)
        end
        rc = libzmq.zmq_msg_close(part)
        if rc == -1 then
            return nil, libzmq.zmq_errno()
        end
    until more

    return msg, nil
end

local function poller_add_item(poller, sock, event)
    table.insert(poller.items, { sock = sock, event = event })
end

local function poller_poll(poller, timeout)
    local events_buffer = ffi.new("struct zmq_pollitem[?]", #poller.items)
    for i, item in ipairs(poller.items) do
        events_buffer[i - 1].socket = item.sock.socket
        events_buffer[i - 1].fd = 0
        events_buffer[i - 1].events = item.event
        events_buffer[i - 1].revents = 0
    end
    local rc = libzmq.zmq_poll(events_buffer, #poller.items, timeout)
    if rc < 0 then
        return nil, libzmq.zmq_errno()
    end
    local result = {}
    local added = 0
    for i = 1, #poller.items do
        if added == rc then
            break
        end
        if events_buffer[i - 1].revents ~= 0 then
            table.insert(result, poller.items[i])
            added = added + 1
        end
    end
    return result
end

local function mk_poller(ctx)
    local p = {
        ctx = ctx,
        items = {},
        add = poller_add_item,
        poll = poller_poll,
    }
    return p
end

local function mk_socket(ctx, socktype)
    local sock = libzmq.zmq_socket(ctx.ctx, socktype)
    return check_if_error(sock,
                          {
                              ctx = ctx.ctx,
                              socket = sock,
                              bind = socket_bind,
                              connect = socket_connect,
                              close = socket_close,
                              disconnect = socket_disconnect,
                              send = socket_send,
                              recv = socket_recv,
                              setsockopt_int = socket_setsockopt_int,
                              setsockopt_str = socket_setsockopt_str,
                          }, nil)
end

local function ctx_new()
    local ctx = libzmq.zmq_ctx_new()
    return check_if_error(ctx,
                          {
                              ctx = ctx,
                              term = ctx_term,
                              socket = mk_socket,
                              poller = mk_poller,
                          }, nil)
end

local P =
    {
        ctx_new = ctx_new,
        PUB = ZMQ_PUB,
        SUB = ZMQ_SUB,
        REQ = ZMQ_REQ,
        REP = ZMQ_REP,
        ROUTER = ZMQ_ROUTER,
        DEALER = ZMQ_DEALER,
        PAIR = ZMQ_PAIR,
        PULL = ZMQ_PULL,
        PUSH = ZMQ_PUSH,
        XPUB = ZMQ_XPUB,
        XSUB = ZMQ_XSUB,
        STREAM = ZMQ_STREAM,

        POLLIN = ZMQ_POLLIN,
        POLLOUT = ZMQ_POLLOUT,
        POLLERR = ZMQ_POLLERR,

        SOCKOPT_RCVTIMEO = ZMQ_RCVTIMEO,
        SOCKOPT_SNDTIMEO = ZMQ_SNDTIMEO,
        SOCKOPT_LINGER = ZMQ_LINGER,
        SOCKOPT_ROUTING_ID = ZMQ_ROUTING_ID,
        SOCKOPT_ROUTER_MANDATORY = ZMQ_ROUTER_MANDATORY,
    }

if _REQUIREDNAME == nil then
    zmq = P
else
    _G[_REQUIREDNAME] = P
end

return P